// NewDagReader creates a new reader object that reads the data represented by
// the given node, using the passed in DAGService for data retreival
func NewDagReader(ctx context.Context, n node.Node, serv mdag.DAGService) (*DagReader, error) {
switch n := n.(type) {
case *mdag.RawNode:
return &DagReader{
buf: NewRSNCFromBytes(n.RawData()),
}, nil
case *mdag.ProtoNode:
pb := new(ftpb.Data)
if err := proto.Unmarshal(n.Data(), pb); err != nil {
return nil, err
}
switch pb.GetType() {
case ftpb.Data_Directory:
// Dont allow reading directories
return nil, ErrIsDir
case ftpb.Data_File, ftpb.Data_Raw:
return NewDataFileReader(ctx, n, pb, serv), nil
case ftpb.Data_Metadata:
if len(n.Links()) == 0 {
return nil, errors.New("incorrectly formatted metadata object")
}
child, err := n.Links()[0].GetNode(ctx, serv)
if err != nil {
return nil, err
}
childpb, ok := child.(*mdag.ProtoNode)
if !ok {
return nil, mdag.ErrNotProtobuf
}
return NewDagReader(ctx, childpb, serv)
case ftpb.Data_Symlink:
return nil, ErrCantReadSymlinks
default:
return nil, ft.ErrUnrecognizedType
}
default:
return nil, fmt.Errorf("unrecognized node type")
}
}
